Accelerated aerogel development via Soxhlet extraction and freeze-drying

Abstract

The tedious and time-consuming solvent exchange during aerogel production was sped up using a standard Soxhlet extractor. Optimizing the setup with a vent and molecular sieve allowed to save up to 80% of the production time compared to batchwise extractions while maintaining state-of-the-art samples of silica and polyurethane aerogels, i.e. MTMS aerogels with a thermal conductivity of 15 mW m⁻¹ K⁻¹ and PU aerogels with 17 mW m⁻¹ K⁻¹ and good mechanical properties even after freeze-drying, which is generally more stressful than supercritical drying. The syntheses had to be carried out in high-boiling solvents, but adaptation and optimisation were made possible rapidly due to the method developed.